Regulation of androgen receptor function by H3K4 methylation in prostate cancer Project Summary The evolution of prostate cancer from an androgen-dependent state (ADPC) to one that is castration- resistant (CRPC) marks the lethal progression of the disease. Understanding the pathogenesis of CRPC and development of novel therapies for CRPC remains an urgent need. The androgen receptor (AR), a ligand-dependent transcription factor, is still expressed and functional in CRPC; however, how AR regulates target genes in CRPC and the functional roles of AR target genes in CRPC is poorly understood. In preliminary studies we have found that AR selectively binds to enhancer regions of M- phase cell cycle genes (e.g. UBE2C) in a CRPC cell model but not in an ADPC cell model, leading to higher M-phase gene expression and faster growth of CRPC than of ADPC. Interestingly, we further found that increased histone H3 lysine 4 (H3K4) methylation level on the M-phase gene enhancers is the underlying mechanism for selective AR binding at M-phase gene enhancers in CRPC compared with ADPC. However, these studies are limited to identifying and characterizing a few enhancer H3K4 methyaltion regulated AR target genes in a pair of CRPC/ADPC cell models. In this proposal we hypothesize that enhancer and promoter H3K4 methylation directs AR in the global regulation of target genes involved in critical processes such as growth and invasion in CRPC. Our specific aims are to: (1) To determine whether the enhancer H3K4 methylation and AR play a causal role in regulating UBE2C expression and to investigate the functional role of UBE2C in various CRPC cell models and in tumorigenesis in vivo. The hypothesis that UBE2C is a direct enhancer H3K4 methylation and AR co- regulated gene that plays a critical role in growth and invasion of at least a subset of CRPC cell models and in tumorigenesis in vivo will be tested in this aim. (2) To globally identify and characterize enhancer/promoter H3K4 methylation and AR co-regulated genes in CRPC cells. The hypothesis that gain of H3K4me2 directs distal enhancer-bound AR to activate oncogenes, whereas loss of H3K4me2 and/or H3K4me3 leads to enhancer- and/or promoter-bound AR-mediated silencing of tumor suppressor genes in CRPC will be tested in this aim. (3) To examine the relevance of H3K4 methylation/AR regulation of target genes in human prostate cancer samples. The hypothesis that the data obtained from Aims 1 and 2 is relevant to human prostate cancer will be evaluated in CRPC and ADPC samples in this aim.